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1.
Water Res ; 195: 116995, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33721675

RESUMO

Membrane fouling is a prominent problem that hinders the stable and efficient operation of the reverse osmosis (RO) system for wastewater reclamation. Previous studies showed that chlorine disinfection, which was commonly used in industrial RO systems as pretreatment, could lead to significant change in microbial community structure and resulted in serious biofouling. In order to prevent biofouling during wastewater reclamation, the effect of ultraviolet (UV) disinfection on RO membrane fouling was investigated and the mechanism was also revealed in this study. With the disinfection pretreatment by UV of 20, 40 and 80 mJ/cm2, the bacteria in the feed water were inactivated significantly with a log reduction of 1.11, 2.55 and 3.61-log, respectively. However, RO membrane fouling aggravated with higher UV dosage. Especially, in the group with the UV dosage of 80 mJ/cm2, the normalized RO membrane flux decreased by 15% compared with the control group after 19-day operation. The morphology of the fouled RO membranes indicated serious biofouling in all groups. The analysis on the microbial amount of the foulants showed that the heterotrophic plate counts (HPC) and ATP content on the fouled RO membranes with and without UV disinfection were at the same level. However, the total organic carbon content of the foulants with the UV dosage of 40 and 80 mJ/cm2 was significantly higher than the control group, with higher content of proteins and polysaccharides as indicated by EEM and FTIR spectrum. Microbial community structure analysis showed that some typical UV-resistant bacteria were selected and remained on the RO membrane after disinfection with high UV dosage, including. These residual bacteria after disinfection with high UV dosage showed higher extracellular polymeric substances (EPS) secretion compared with those without UV disinfection, and thus aggravated RO membrane fouling. Thicker EPS could decrease the transmission of UV rays, and thus bacteria with higher EPS secretion might be selected after UV disinfection.


Assuntos
Incrustação Biológica , Purificação da Água , Desinfecção , Membranas Artificiais , Osmose , Águas Residuárias
2.
J Asian Nat Prod Res ; : 1-10, 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33550877

RESUMO

Eighteen novel 3/5(3,5)-(di)nitropaeonol hydrazone derivatives were prepared, and their structures well characterized by 1H NMR, HRMS, and mp. Due to the steric hindrance, the substituents on the C = N double bond of all hydrazine compounds (except E/Z = 4/1 for IV-1g, IV-1l, IV-2b, and E/Z = 3/2 for IV-1n, IV-3a) adopted E configuration. Among all compounds, four compounds 2, 4, IV-1j, and IV-1n exhibited potent nematicidal activity than their precursor paeonol, especially 5-nitropaeonol (2) and 3,5-dinitropaeonol (4) displayed the most potent nematicidal activity Heterodera glycines in vivo with LC50 values of 32.3307 and 36.7074 mg/L, respectively.

3.
J Hazard Mater ; 413: 125283, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33582467

RESUMO

Microbial extracellular polymeric substances (EPS) have a profound role in various wastewater treatment and reclamation processes, in which a variety of technologies are used for disinfection and microbial growth inhibition. These treatment processes can induce significant changes in the quantity and properties of EPS, and altered EPS could further adversely affect the wastewater treatment and reclamation system, including membrane filtration, disinfection, and water distribution. To clarify the effects of microbial inactivation approaches on EPS, these effects were classified into four categories: (1) chemical reactions, (2) cell lysis, (3) changing EPS-producing metabolic processes, and (4) altering microbial community. Across these different effects, treatments with free chlorine, methylisothiazolone, TiO2, and UV irradiation typically enhance EPS production. Among the residual microorganisms in EPS matrices after various microbial inactivation treatments, one of the most prominent is Mycobacterium. With respect to EPS properties, proteins and humic acids in EPS are usually more susceptible to treatment processes than polysaccharides. The affected EPS properties include changes in molecular weight, hydrophobicity, and adhesion ability. All of these changes can undermine wastewater treatment and reclamation processes. Therefore, effects on EPS quantity and properties should be considered during the application of microbial inactivation and growth inhibition techniques.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33605007

RESUMO

Chiral carboxylic acids are important compounds because of their prevalence in pharmaceuticals, natural products and agrochemicals. Asymmetric hydrogenation of α , ß -unsaturated carboxylic acids has been widely recognized as one of the most efficient synthetic approaches to afford such compounds. Although related asymmetric hydrogenation of di - and tri -substituted unsaturated acids with noble metals has been well established, asymmetric hydrogenation of challenging tetra -substituted α , ß -unsaturated carboxylic acids is rarely reported. Herein, we demonstrate enantioselective hydrogenation of both cyclic and acyclic tetra -substituted α , ß -unsaturated carboxylic acids via cobalt(II) catalysis. This protocol showed broad substrate scope and gave chiral carboxylic acids in good yields with excellent enantiocontrol (up to 98% yield and 99% ee). The combined experimental and computational mechanistic studies collectively support a Co(II) catalytic cycle involving migratory insertion and sigma-bond metathesis processes. In addition, our DFT calculations revealed that the enantioselectivity may origin from the steric effect between the phenyl groups of the ligand and the substrate.

5.
J Am Chem Soc ; 143(6): 2477-2483, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33529522

RESUMO

A catalytic protocol for the enantio- and diastereoselective reduction of α-substituted-ß-keto carbonitriles is described. The reaction involves a DKR-ATH process with the simultaneous construction of ß-hydroxy carbonitrile scaffolds with two contiguous stereogenic centers. A wide range of α-substituted-ß-keto carbonitriles were obtained in high yields (94%-98%) and excellent enantio- and diastereoselectivities (up to >99% ee, up to >99:1 dr). The origin of the diastereoselectivity was also rationalized by DFT calculations. Furthermore, this methodology offers rapid access to the pharmaceutical intermediates of Ipenoxazone and Tapentadol.

6.
Water Res ; 188: 116474, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33039832

RESUMO

Chlorine-resistant bacteria (CRB) are commonly defined as bacteria with high resistance to chlorine disinfection or bacteria which can survive or even regrow in the residual chlorine. Chlorine disinfection cannot completely control the risks of CRB, such as risks of pathogenicity, antibiotic resistance and microbial growth. Currently, researchers pay more attention to CRB with pathogenicity or antibiotic resistance. The microbial growth risks of non-pathogenic CRB in water treatment and reclamation systems have been neglected to some extent. In this review, these three kinds of risks are all analyzed, and the last one is also highlighted. In order to study CRB, various methods are used to evaluate chlorine resistance. This review summarizes the evaluating methods for chlorine resistance reported in the literatures, and collects the important information about the typical isolated CRB strains including their genera, sources and levels of chlorine resistance. To our knowledge, few review papers have provided such systematic information about CRB. Among 44 typical CRB strains from 17 genera isolated by researchers, Mycobacterium, Bacillus, Legionella, Pseudomonas and Sphingomonas were the five genera with the highest frequency of occurrence in literatures. They are all pathogenic or opportunistic pathogenic bacteria. In addition, although there are many studies on CRB, information about chlorine resistance level is still limited to specie level or strain level. The difference in chlorine resistance level among different bacterial genera is less well understood. An inconvenient truth is that there is still no widely-accepted method to evaluate chlorine resistance and to identify CRB. Due to the lack of a unified method, it is difficult to compare the results about chlorine resistance level of bacterial strains in different literatures. A recommended evaluating method using logarithmic removal rate as an index and E. coli as a reference strain is proposed in this review based on the summary of the current evaluating methods. This method can provide common range of chlorine resistance of each genus and it is conducive to analyzing the distribution and abundance of CRB in the environment.


Assuntos
Cloro , Purificação da Água , Desinfecção , Resistência Microbiana a Medicamentos , Escherichia coli , Microbiologia da Água
7.
Chem Commun (Camb) ; 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33300017

RESUMO

Phosphine-oxazoline (PHOX) ligands are a very important class of privileged ligands in asymmetric catalysis. A series of highly rigid oxa-spiro phosphine-oxazoline (O-SIPHOX) ligands based on O-SPINOL was synthesized efficiently, and their iridium complexes were synthesized by coordination of the O-SIPHOX ligands to [Ir(cod)Cl]2 in the presence of sodium tetrakis-3,5-bis(trifluoromethyl)phenylborate (NaBArF). The cationic iridium complexes showed high reactivity and excellent enantioselectivity in the asymmetric hydrogenation of 1-methylene-tetrahydro-benzo[d]azepin-2-ones (up to 99% yield and up to 99% ee). A key intermediate of the anti-obesity drug lorcaserin could be efficiently synthesized using this protocol.

8.
J Hazard Mater ; : 124602, 2020 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-33234394

RESUMO

Chlorine disinfection is a common technology to control biofouling in the pretreatment of the reverse osmosis (RO) system for wastewater reclamation. However, chlorine disinfection could even aggravate the RO membrane biofouling because of the changes of microbial community structure. In this study, the mechanism of biofilm formation and EPS secretion after chlorine disinfection was investigated by analyzing the genes coding quorum sensing, exopolysaccharide biosynthesis, and amino acid biosynthesis. After 1, 5, and 15 mg-Cl2/L chlorine disinfection, the relative abundances of the functional genes all increased significantly. Compared with the control group, chlorine-resistant bacteria (Acidovorax, Arenimonas, and Pseudomonas) also harbored higher relative abundances of these functional genes. The high relative abundances of these genes might provide the bacterial community after chlorine disinfection with high potential of biofilm formation and EPS secretion and then cause severe RO membrane biofouling. In the sample with 5 mg-Cl2/L chlorine disinfection, the correlation coefficients (r) between each two of the three kinds of functional genes were more than 0.9 and much stronger than that in the control group. These results indicated that the bacterial community selected by chlorine disinfection could build more stable biofilm to resist chlorine but also could cause more severe RO membrane biofouling.

9.
Chem Commun (Camb) ; 2020 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-33244528

RESUMO

Chiral α-hydroxy-ß-lactams are key fragments of many bioactive compounds and antibiotics, and the development of efficient synthetic methods for these compounds is of great value. The highly enantioselective dynamic kinetic resolution (DKR) of α-keto-ß-lactams was realized via a novel proton shuttling strategy. A wide range of α-keto-ß-lactams were reduced efficiently and enantioselectively by Ni-catalyzed asymmetric hydrogenation, providing the corresponding α-hydroxy-ß-lactam derivatives with high yields and enantioselectivities (up to 92% yield, up to 94% ee). Deuterium-labelling experiments indicate that phenylphosphinic acid plays a pivotal role in the DKR of α-keto-ß-lactams by promoting the enolization process. The synthetic potential of this protocol was demonstrated by its application in the synthesis of a key intermediate of Taxol and (+)-epi-Cytoxazone.

10.
Org Lett ; 22(22): 8882-8887, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-33147038

RESUMO

Asymmetric hydrogenation of 2-aryl-3-phthalimidopyridinium salts catalyzed by the Ir/SegPhos catalytic system was described, leading to the corresponding chiral piperidine derivatives bearing two contiguous chiral centers, with high levels of enantioselectivities and diastereoselectivities. A gram-scale experiment has demonstrated the utility of this approach. The phthaloyl group could be easily removed and then smoothly converted to key intermediate (+)-CP-99994 as one of the neurokinin 1 receptor antagonists.

11.
Nat Commun ; 11(1): 3239, 2020 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-32591536

RESUMO

Asymmetric hydrogenation of α,ß-unsaturated acids catalyzed by noble metals has been well established, whereas, the asymmetric hydrogenation with earth-abundant-metal was rarely reported. Here, we describe a cobalt-catalyzed asymmetric hydrogenation of α,ß-unsaturated carboxylic acids. By using chiral cobalt catalyst bearing electron-donating diphosphine ligand, high activity (up to 1860 TON) and excellent enantioselectivity (up to >99% ee) are observed. Furthermore, the cobalt-catalyzed asymmetric hydrogenation is successfully applied to a broad spectrum of α,ß-unsaturated carboxylic acids, such as various α-aryl and α-alkyl cinnamic acid derivatives, α-oxy-functionalized α,ß-unsaturated acids, α-substituted acrylic acids and heterocyclic α,ß-unsaturated acids (30 examples). The synthetic utility of the protocol is highlighted by the synthesis of key intermediates for chiral drugs (6 cases). Preliminary mechanistic studies reveal that the carboxy group may be involved in the control of the reactivity and enantioselectivity through an interaction with the metal centre.

12.
J Asian Nat Prod Res ; : 1-11, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32406756

RESUMO

Two series of sulfonate derivatives of carvacrol and thymol were synthesized and screened in vitro for their anti-oomycete activity against Phytophthora capsici, respectively. Among all of 32 derivatives, five compounds 3a, 4a, 4k, 3n, and 4n exhibited more potent anti-oomycete activity against P. capsici with EC50 values of 66.66, 62.94, 68.65, 61.24, and 52.91 mg/L, respectively. This suggested that introduction of different substitutions at the hydroxyl position of 1/2 could have remarkable effect on anti-oomycete activity. Overall, when R1 = isopropyl and R2 = methyl, the anti-oomycete activities of the compounds were higher than that of the corresponding compounds of R1 = methyl and R2 = isopropyl.[Formula: see text].

13.
J Asian Nat Prod Res ; : 1-13, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32091234

RESUMO

Endeavor to discover biorational natural products-based insecticides, two series (27) of novel 9R/S-acyloxy derivatives of cinchonidine and cinchonine were prepared and assessed for their insecticidal activity against Mythimna separata in vivo by the leaf-dipping method at 1 mg/mL. Among all the compounds, especially derivatives 6l and 6o exhibited the best insecticidal activity with final mortality rates of 75.0% and 71.4%, respectively. Overall, a free 9-hydroxyl group is not a prerequisite for insecticidal activity and C9-substitution is well tolerated; the configuration of C8/9 position is important for insecticidal activity, and 9S-configuration is optimal; 6'-OCH3 moiety is not necessary, removal of it is also acceptable.

14.
Chem Commun (Camb) ; 56(21): 3119-3122, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32090223

RESUMO

A highly efficient diastereoselective transfer hydrogenation of α-aminoalkyl α'-chloromethyl ketones catalyzed by a tethered rhodium complex was developed and successfully utilized in the synthesis of the key intermediates of HIV protease inhibitors. With the current Rh(iii) catalyst system, a series of chiral 3-amino-1-chloro-2-hydroxy-4-phenylbutanes were produced in excellent yields and diastereoselectivities (up to 99% yield, up to 99 : 1 dr). Both diastereomers of the desired products could be efficiently accessed by using the two enantiomers of the Rh(iii) catalyst.


Assuntos
Complexos de Coordenação/química , Cetonas/química , Ródio/química , Catálise , Inibidores da Protease de HIV/síntese química , Hidrogenação , Ligantes , Estrutura Molecular , Oxirredução , Estereoisomerismo , Relação Estrutura-Atividade
15.
J Asian Nat Prod Res ; : 1-12, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32009450

RESUMO

Three series of sulfonate derivatives of paeonol were synthesized and screened in vitro for their anti-oomycete activity against P. capsici, respectively. Among all the compounds, 4m displayed the best promising and pronounced anti-oomycete activity against P. capsici than zoxamide, with the EC50 values of 24.51 and 26.87 mg/L, respectively. The results show that acetyl and 4-OCH3 are two necessary groups. The existence of these two sites is closely related to the anti-oomycete activity. Relatively speaking, hydroxyl group is well tolerated, and the results showed that after modification of hydroxyl group with sulfonyl, the anti-oomycete activity was significantly increased.[Formula: see text].

16.
Comb Chem High Throughput Screen ; 23(3): 232-238, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31985371

RESUMO

BACKGROUND: Plant secondary metabolites play an essential role in the discovery of novel insecticide due to their unique sources and potential target sites. Paeonol, the main phenolic components in Moutan Cortex, is recognized as a safe and potent botanical insecticide to many insects. The structural modification of paeonol in this study into phenylsulfonylhydrazone derivatives is proved an effective approach for the development of novel insecticides, those derivatives being more toxic than paeonol. However, there have been no reports on the insecticidal activity of paeonol-based phenylsulfonylhydrazone derivatives in controlling Mythimna separata. METHODS: We have been working to discover biorational natural products-based insecticides. Twelve novel paeonol-based phenylsulfonylhydrazone derivatives have been successfully prepared by structural modification of paeonol, and the insecticidal activity against M. separata by the leafdipping method at the concentration of 1 mg/mL has been evaluated. RESULTS: Insecticidal activity revealed that out of 12 title compounds, derivatives 5c and 5f displayed the best against M. separate with the FMR both of 53.6% than toosendanin (FMR = 50.0%). CONCLUSION: The results suggested that for the paeonol-based phenylsulfonylhydrazone series derivatives, the proper substituent of arylsulfonyl R at the hydroxyl position of paeonol was very important for their insecticidal activity. These preliminary results will pave the way for further modification of paeonol in the development of potential new insecticides.

17.
Org Lett ; 22(3): 858-862, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31916775

RESUMO

A copper-catalyzed asymmetric hydrosilylation of ß-nitroethyl aryl ketones has been disclosed, and the corresponding chiral alcohols could be obtained in high yields (up to 99% yield) and excellent enantioselectivities (up to 96% ee). Moreover, the reaction worked well on a gram scale with 0.3 mol % of ligand loading, indicating that our protocol has potential applications in the synthesis of important pharmaceuticals such as Tranylcypromine and Ticagrelor.

18.
J Asian Nat Prod Res ; 22(12): 1197-1206, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31773971

RESUMO

Gramine can be intelligently and efficiently supplied with N, N-dimethylamino group and then reacted with the corresponding sulfonyl chlorides to synthesize N, N-dimethylarylsulfonamides. We herein designed and controlled synthesis of N, N-dimethylarylsulfonamide derivatives, and first reported the results of the nematicidal activity of 15 title compounds 3a-o against Meloidogyne incongnita in vitro, respectively. Among all of the title derivatives, compounds 3a, 3c, 3k, and 3o exhibited potent nematicidal activity with median lethal concentration (LC50) values ranging from 0.22 to 0.26 mg/L. Most noteworthy, N, N-dimethyl-4-methoxyphenylsulfonamide (3c) and N, N-dimethyl-8-quinolinesulfonamide (3o) showed the best promising and pronounced nematicidal activity, with LC50 values of 0.2381 and 0.2259 mg/L, respectively.


Assuntos
Antinematódeos , Tylenchoidea , Animais , Antinematódeos/farmacologia , Estrutura Molecular
19.
J Asian Nat Prod Res ; 22(6): 578-587, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31046458

RESUMO

Sixteen sulfonate derivatives of maltol were synthesized and screened in vitro for their anti-oomycete and nematicidal activity against Phytophthora capsici and Bursaphelenchus xylophilus, respectively. Among all the compounds, 3e, 3m, and 3p exhibited the most promising and pronounced anti-oomycete activity against P. capsici than zoxamide, and the EC50 values of 25.42, 18.44, 23.69, and 27.99 mg/L, respectively; compounds 3e, 3m, 3n, and 3p exhibited potent nematicidal activity with LC50 values ranging from 1 to 2 mg/L, especially 3m and 3n showed the best promising and pronounced nematicidal activity, with LC50 values of 1.1762 and 1.2384 mg/L, respectively. [Formula: see text].


Assuntos
Phytophthora , Antinematódeos , Estrutura Molecular , Pironas
20.
J Asian Nat Prod Res ; 22(7): 678-688, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31120307

RESUMO

A series of sulfonate derivatives of sesamol were synthesized and evaluated for their insecticidal activity against a crop-threatening agricultural pest, the pre-third-instar larvae of Mythimna separata in vivo. Among all the target compounds, compounds 3b, 3g, 3h, and 3p exhibited more promising insecticidal activity than sesamol and toosendanin, and the final mortality rates (FMRs) of 3b, 3g, 3h, 3p, 1, and toosendanin were 60.7%/60.7%/67.9%/53.6%/32.1%/50.0%, respectively. Especially compound 3h exhibited the most potent insecticidal activity with FMRs of 67.9%. This suggested that a 4-fluorophenylsulfonyl group introduced at the hydroxyl position of sesamol was necessary for obtaining the most potent compound.[Formula: see text].


Assuntos
Inseticidas , Mariposas , Animais , Benzodioxóis , Larva , Estrutura Molecular , Fenóis
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